Improvement in magic lanterns



C. FONTAYNE.

Magic-Lantern.

N 57 090 Patented Aug. 24,1875.

WITNESSES.

. lNVENTOR.

NPEYERS, PHOTQ-LITHOGRAPNER, WBNINGYON, D C.

UNI ED STATES PATENT OFFICE.

CHARLES FONTAYNE, OF NEW YORK, N. Y.

IMPROVEMENT IN MAGIC LANTERNS.

Specification. forming part of Letters Patent No. [67,090, dated August24, 18 5 application filed I July 9, 1875.

I and. the invention consists in the combination of a movable reflectorwith a magnifying-lens in suchv manner that, the axis of the support ofsaid reflector forms such an angle with the axis of the lens as toprevent the projection of the. image of the burner on the screen, aswill hereinafter be. more fully described.

Figure 1 is a side elevation of the lamp and a. longitudinal section ofthe lantern. Fig. 2

v isa rear end view to show one method of supporting the rear reflector.Fig. 3 is a plan to show a modified form of the lantern when adapted forexhibiting opaque pictures.

AtA is. represented a common form of oillamp, the base of which mayserve as a base for theentire lantern,as shown in Fig. 1. Surroundingsaid lamp, and upon its base, is mounted the conical support of thelantern, as at B, and said support is tubular, and serves. as a guidefor the air to the lamp, as well as a. base. for the lantern. Upon saidbase or support. B is mounted the body of thelantern proper, as at G,and this is preferably made in the form shown. in Fig. 1, though it maybe greatly varied, as will appear hereafter. Said body is. the frustumof a cone, and upon the base thereof is mounted the chief reflector D,which is a large concave reflector, that may be made-of any materialdesired; but the wellknown glass reflectors with a silver coatinganswers the purpose, and is probably the cheapest for. the purpose atpresent known. Said reflector is mounted upon a ring or hoop of metal,as at E, which surrounds its edge, and itmay be stayed and held in saidring by straps of metal, as at F, extending from the ring E across andover the back of the reflector, as. shown in thedrawings.

As it is essential that the reflector shall be capable of adjustment invarious directions,

rounding the base of the cone 0, and said ring G is mounted on pivots atright angles to the first, so that the reflector is capable. of anymovement, as the mariners compass. But another method of mounting thereflector is shown at Fig. 2, and as. it answers every pur-- pose, andis made cheaper, is the preferred method, and it consists in mountingthe ring E within the cone O by suspending it upon a loop or pin, as atg, which. projects through the base of the cone 0, and is suspended by apin or split ring, as shown in Fig. 2, which holds the reflectorsuspended. within the base of the cone 0, and then toadjust it at theproper angles and hold it small springs, as at H, are attached upon theouter portion of the ring E, and they serve to produce sufficientfriction between the ringE and the inner band that surrounds the baseofv the cone as to hold the reflector at any required adjustment. Uponthe small end of the cone 0 is mounted the tube, as at K, for holdingthe. picture and the magnifying-lens.that is, if the pictures betransparent, or made for the. light. to pass through them, in which casethe tubeis constructed as shown at Fig. 1; but if the pictures areopaque then the front tube is placed at an angle upon the side ofthecone O, as shown at Fig. 3, and the picture is placed in the base ofthe tube K, and receives its illumination from the reflector D upon itsface, insteadof through it, as in Fig. 1. The principal of illuminationis, however, the same in both. Now,I have discovered that by making theinterior surface of the cone 0 a bright reflecting-surface, and placingthe source of light within it, and then mount a large reflector withinits base at such an angle that its axis will form an angle to the axisof the magnifying-lens, or by tilting it to such a degree as not toproject the image of the lamp-burner upon the screen, that thecombination of the two reflecting-surfaces will give a most powerfulillumination of the pictures without the use of a condensing-lens, I

or any other corresponding to it, and that by such a simple combinationa very cheap. lantern can be produced that will give as good results asinstruments costing from five to ten times as much. To determine theproper angle of the cone 0 it depends upon the size of the picture, andif it is transparent then it will be mounted in a tube, as at Fig. l,where a slit it made through the tube, and as close as possible to theend of the cone 0, for it must be borne in mind that the nearer thepicture is to the source of the light the better it will be as less ofit is absorbed in its passage, as is now the casein the use of acondensing-lens.

The size of the pictures being determined, then the next thing is tochoose the concave reflector D, which should be as large as possible tocollect all the rays that can be transmitted to the picture, and thesize of said reflector is only limited by its proximity or relationshipto the light, and the concavity of the reflector itself, and it shall beplaced as near to the light as possible, merely allowing suflicientspace for adjustment to focus with the picture and the magnifying-lens.

Thesethreeelementshavingbeen determined upon, viz, size of picture, sizeof concave reflector, and possible distance from the burner to avoidinjury from heat, and to permit adjustment, then the form and size ofthe cone are easily determined, as it is evident that its small end nextto the picture must be the size to be illuminated, or practically thesize of the picture, and the other end must be sufficiently large toadmit the concave reflector within its base, as shown at Fig. 1, and itslength must be as short as possible to'prevent injuring the picture orthe reflector by the heat from the'lainp, and then the inside of saidcone must be polished or silvered to produce a reflecting-surface thatwill catch all divergent rays of light in front of the burner or betweenit and the picture, and also all others that would otherwise be lost,and throw them into or converge them upon the surface of the largeconcave reflector, as at D, and by which they are thrown upon thepicture without the use of any costly lens, either directly orindirectly.

The rest of the apparatus may now be easily understood, as the size anddiameter of the front tube K depend upon the size of the magnitying-lensdesired to be used, and the only thing to be determined as to the lengthof said tube is that the magnifying-lens, as at 0, must be placedbetween the picture and the focus of the concave reflector D. Whentransparent pictures are used, the lens, as at 0, may be mounted in asliding tube as at};

to assist in adjustment, as is now commonly done. If, however, opaquepictures are to be shown, then the front tube K must be placed, as shownin Fig. 3, at the side of the cone reflector O, and the picture must bemounted, as at R, at an angle of about forty-five degrees or less, ifpossible, to the plane of the mirror D, so that the illuminating-rayswill be reflected from the picture through the magnifier instead ofbeing transmitted.

It is evident, however, that the principle of illumination, which is theessence of my invention, is the same in both; and it is also evidentthat the lamp and the illuminatingcone 0 may be mounted in a box or caseindependent of each other, and yet so related to the light and theconcave reflector and the picture, that my method of illuminationwithout the use of a condensing-lens will be employed; but it ismanifest that this construction, as represented, is less expensive.

It will be observed that the reflector D is placed in the base of thecone G at an inclination with its top toward the chimney of the lamp,and this is done in order to avoid reflecting the image of the burnerupon the screen, and at the same time permit the light to be placednearer to the concave mirror than the length of the radius of a sphere,of which the mirror would represent a segment.

This relationship of the mirror to the source of light constitutes avaluable discovery of itself, apart from the use of thecone 0, as it ispossible to-bring the convergent rays of the large reflector D so nearto the picture that an excellent illuminating-cone is obtained withoutbeing injured by the image of'theburner or its chimney, or the flameitself,

which is always the case when the illuminating-point is placed in a linecoincident with the axis of the reflector and the lens, and

thus it is possible to obtain good results by I mounting the reflector,as already stated, at

such an angle to the magnifying-lens as that the image of the burnerwill be thrown out of the illuminating-cone, and will not, therefore,appear upon the screen. Such an arrangement of the reflector alsopermits the use of i a greater segment of a sphere than has heretoforebeen done, and, at the same time, permits the picture to be producednearer to the source of light than is possible to do without acondenser, or without destroying the picture by the heat. In fact, I amnot aware that any lantern can use a reflector of so large a surface,and having so short a radius, with the light between it and the picture,and

thereby produce such a powerful illuminating- 1 cone without acondensing-lens, which is the costliest element of such lanterns.

A plane of glass, as at It, is fastened in the small end of the cone 0,to cut off the heat from the picture which is inserted at S, and betweenthe two is a space left, or with holes, as at T, through which the airmay pass to keep the picture or delicate specimens from being injured.Such improvements are also manifest in the exhibition of opaquepictures, as it will be seen that if a condensing-lens can be dispensedwith, then the reflector D may be brought round to more nearly face thepicture than is even shown at Fig. 3', and yet there will be nothing toobstruct the reflected rays, as would be the case were a con-A denserinterposed. It is also evident that such a combination of the cone withthe reflector and the burner is well adapted for all 2. In combinationwith the reflector D and purposes of illumination where the rays of thecone 0, the springs H for holding the relight are to be collected andconverged forflector D in proper position when once adward, as in thehead-light of locomotives, justed, substantially as described.

vessels at sea, &c.; and 3. The combination of the reflectors D and Itherefore c1aim G, with the pivoted bearings between the tWo,- 1. In amagic lantern, the combination of a substantially as described.

reflector with a magnifying-lens, when the axis of the support of saidreflector forms CHAS. FONTAYNE. such an angle with the axis of thelens'as to Attest: prevent the projection of the image of the E. B.GOODRICH, burner on the screen. 1 BoYD ELIOT.

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